The present invention relates to a pair of eyeglasses of the type having a bridge joining the edges of the lenses and a nose rest that can be mounted on the side of the bridge facing toward the wearer.
Proper positioning of a glasses frame is of critical importance because this defines the path of incident light into the eyes, and hence the intended optical effect, while an anatomically unfavorable or unskilled positioning can cause impairments and in particular discomfort to the wearer and damage to the skin where the glasses rest.
These two problem areas are intrinsically interrelated, and the actual problem arises from the fact that the relevant anatomical features in the head region, that is the region of the root and sides of he nose and in region around the ears, are different in every person and also differ from one another in persons of different races.
It suffices to mention here only the variation in the width of the forehead by up to 10 mm, the shape and width of the nose, and so forth. The anatomical features which are particularly relevant in the design of a glasses frame can be found in an article by Dieter Fahrner published in NOJ 11/1990, pp. 8 to 19.
If it is to be possible to position the eyeglasses frame on any individual wearer in a satisfactory way from both an optical and an anatomical standpoint, structural designs are necessary that can be adapted in some way sufficiently so that the optical wearing situation for a given wearer is attainable at least in rough approximation. In principle this adaptation can be attained in two different ways: namely by means of a structural part that is intrinsically variable in shape, or one that is available in different sizes and dimensions. It is then the task of the optician, for an industrially manufactured glasses frame, to make such changes with skill or to select properly fitting component parts, to enable individual adaptation to the wearer. For instance, manufacturers offer glasses frames in three different bridge widths (16 mm, 18 mm and 20 mm), to make possible at least a rough adaptation to the width of the bridge of the nose of the particular wearer.
In narrowly defined regions, adaptations to the anatomical features of the wearer can also be attained by means of a soft or elastic embodiment, as is for instance known from the use of silicone as a sheathing material, which has the additional advantage of great comfort while being worn.